4,4′-Bipyridine axially coordinated binuclear cobaloxime complexes as molecular catalysts for light-driven hydrogen evolution

Abstract

Reactions of [Co(dmgH)(dmgH2)Cl2] (dmgH = dimethylglyoxime) or [Co(chdH)(chdH2)Cl2] (chd = 1,2-cyclohexanedione dioximate) with 4,4′-bipyridine in MeOH in the presence of Et3N resulted in the formation of binuclear cobaloxime complexes [{Co(dmgH)2Cl}2(bipy)] (1, bipy = 4,4′-bipyridine) and [{Co(chdH)2Cl}2(bipy)] (2) in good yields. Complexes 1 and 2 were characterized by NMR and X-ray crystallography. Both 1 and 2 were found to be molecular catalysts for light-driven hydrogen evolution in the presence of Eosin Y as photosensitizer and triethanolamine as sacrificial electron donor in aqueous acetonitrile solutions upon irradiation.